Peripheral Nerve Injury Induces Immediate Increases in Layer V Neuronal Activity

Background. Peripheral nerve injury leads to changes in neuronal activity in the contralateral and ipsilateral primary somatosensory cortices (S1), which may lead to enduring sensory dysfunction and pain. Plasticity in the barrel and visual cortices has been shown to occur in a layer-specific manner. However, little is known about the layer specific changes associated with limb injury. Objective. To determine the layer-specific changes in neuronal activity associated with short-term plasticity induced by peripheral nerve injury in the rat. Methods. In vivo electrophysiology recordings (multiunit activity and local field potential) and high-resolution functional magnetic resonance imaging techniques were applied to characterize neuronal and hemodynamic responses across the depth of S1 contralateral and ipsilateral to the injury. Results. Within 60 minutes following injury, atypical increases in neuronal and hemodynamic responses in the deprived S1, ipsilateral to the noninjured limb, were observed in respo...